A false negative can happen for any one of the following reasons:
1. Quetext doesn't yet know about the source of the plagiarized text
We have one of the largest databases of full-text sources in the industry, but it is impossible to know about every word that exists at all times. For example, if an online news article was only written 2 hours ago, it is likely that our web-crawler has not found it yet.
2. Quetext doesn't have access to the source text
Not all text that exists 'online' is able to be indexed (searchable). For example, a piece of research available only through a paid subscription to a specific journal repository. Our search engine contains billions of sources, but some sources are simply not possible to include in our searchable database.
3. Your text has been reworded, and is not similar enough to the original source
If your text was taken from somewhere else, and reworded, the extent to which your text is considered a similar match depends on how much it has been changed. We match your text based on several factors, one of which is the similarity score. For example, if you've altered a piece of text such that it's only 60% similar to the source, we will not consider that a 'match'.